$300 isn't that high of a price to pay for a pad that's going to last for quite a while. You can get metal pads for as cheap as $100-$200, but they're not going to hold up like a Flux would.
I bought my Flux used for $150 and it's gone through a few tournaments as well as a lot of stomping from the previous owner (and me). Aside from a few scuffed panels, the thing's in perfect shape.